Active distributed mode actuator

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for changing a distributed mode loudspeaker&#39;s fundamental frequency. One of the systems includes a distributed mode loudspeaker comprising an actuator that includes: a supported portion, and a cantilevered portion having a length, a first fundamental frequency, and adapted to create a force to cause vibration of a load to generate sound waves using the first fundamental frequency; a support element connected to the supported portion of the actuator and adapted to adjust, based on a change to a shape of the support element, a size of the length of the cantilevered portion to change the first fundamental frequency to a second fundamental frequency with which the load will generate sound waves; and a frequency selection module that provides a signal to the support element to cause the support element to change shape.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/848,292, filed Dec. 20, 2017, the contents of which are incorporatedby reference herein.

BACKGROUND

Some devices use a distributed mode loudspeaker (“DML”) to generatesound. A DML is a speaker that creates sound by causing a panel tovibrate. A DML may use a distributed mode actuator (“DMA”), e.g., apiezoelectric transducer, to cause the panel to vibrate and generatesound instead of a voice coil actuator. For instance, a smartphone mayinclude a DMA that applies force to a display panel (e.g., a LCD or anOLED panel) in the smartphone. The force creates vibrations of thedisplay panel that couple to surrounding air to generate sound waves,e.g., in the range of 20 Hz to 20 kHz which may be audible to a humanear.

SUMMARY

To allow a distributed mode loudspeaker (“DML”) to adjust a fundamentalfrequency with which the DML generates sound waves, the DML adjusts alength of a cantilevered portion of a distributed mode actuator (“DMA”)included in the DML. This allows the DML to generate a wider range offrequencies based on an output mode, a volume of the output sound,content included in an output sound, or a combination of two or more ofthese. Generation of a wider range of frequencies may allow a DML tomore accurately reproduce sounds.

For instance, a DML may include a DMA with a supported portion and acantilevered portion. The DMA has a first fundamental frequency based ona first length of the cantilevered portion. The DML generates soundswithin a first frequency range defined by the first fundamentalfrequency, e.g., a low frequency range.

To enable the DML to dynamically generate sounds within a secondfrequency range different from the first frequency range, e.g., a higherfrequency range, the DML changes a length of the supported portion ofthe DMA which causes the first length of the cantilevered portion tochange, i.e., because the total length of the DMA remains substantiallyconstant. For example, the DML may increase the length of the supportedportion which causes a decrease in the first length of the cantileveredportion and an increase in the fundamental frequency of the DMA.Alternatively, when the DML decreases the length of the supportedportion, the first length increases and the fundamental frequency of theDMA decreases.

The DML may include a frequency selection module, e.g., a digital signalprocessor (“DSP”), that provides a signal to a support. When the supportreceives the signal, a length of the support changes, causing a changein the length of the supported portion of the DMA and the first lengthof the cantilevered portion and causing a change in the fundamentalfrequency of the DML.

The frequency selection module may determine a change to the fundamentalfrequency using an output mode of the DML, a content type for a soundthat the DML will generate, a volume for a sound that the DML willgenerate, or a combination of two or more of these. For instance, thefrequency selection module may determine whether a device that includesthe DML, such as a smartphone, will output sound in a “hands free” mode,e.g., using a speakerphone, or a handheld mode as the output mode. Thefrequency selection module may select a lower fundamental frequency fora handheld mode and a higher fundamental frequency for a hands freemode. In some examples, the frequency selection module may select alower fundamental frequency for generation of lower volume sounds or ahigher fundamental frequency for generation of higher volume sounds.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in methods that include the actionsof receiving, by a distributed mode loudspeaker, a signal representing asound to generate; determining, by a frequency selection module in thedistributed mode loudspeaker, whether to change a current fundamentalfrequency of an actuator included in the distributed mode loudspeaker;sending, by the frequency selection module, a signal to a supportelement based on the determination whether to change the currentfundamental frequency of the actuator; and after sending the signal tothe support element, providing, by the distributed mode loudspeaker, anactivation signal to the actuator to cause the actuator to generate aforce that vibrates a load which generates the sound. Other embodimentsof this aspect include corresponding computer systems, apparatus, andcomputer programs recorded on one or more computer storage devices, eachconfigured to perform the actions of the methods. A system of one ormore computers can be configured to perform particular operations oractions by virtue of having software, firmware, hardware, or acombination of them installed on the system that in operation causes orcause the system to perform the actions. One or more computer programscan be configured to perform particular operations or actions by virtueof including instructions that, when executed by data processingapparatus, cause the apparatus to perform the actions.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a system that includes adistributed mode loudspeaker comprising an actuator that includes: asupported portion, and a cantilevered portion having a length, a firstfundamental frequency, and adapted to create a force to cause vibrationof a load to generate sound waves using the first fundamental frequency;a support element connected to the supported portion of the actuator andadapted to adjust, based on a change to a shape of the support element,a size of the length of the cantilevered portion to change the firstfundamental frequency to a second fundamental frequency with which theload will generate sound waves; and a frequency selection module thatprovides a signal to the support element to cause the support element tochange shape. Other embodiments of this aspect include correspondingcomputer systems, methods, and computer programs recorded on one or morecomputer storage devices, each configured to perform the actions of theoperations. The computer system may include one or more computers andcan be configured to perform particular operations or actions by virtueof having software, firmware, hardware, or a combination of theminstalled on the system that in operation causes or cause the system toperform the actions. One or more computer programs can be configured toperform particular operations or actions by virtue of includinginstructions that, when executed by data processing apparatus, cause theapparatus to perform the actions.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in a system or apparatus thatincludes a smartphone comprising: a display configured to presentcontent; and a distributed mode loudspeaker comprising: an actuator thatincludes: a supported portion, and a cantilevered portion having alength, a first fundamental frequency, and adapted to create a force tocause vibration of a load to generate sound waves using the firstfundamental frequency; a support element connected to the supportedportion of the actuator and adapted to adjust, based on a change to ashape of the support element, a size of the length of the cantileveredportion to change the first fundamental frequency to a secondfundamental frequency with which the load will generate sound waves; anda frequency selection module that provides a signal to the supportelement to cause the support element to change shape. Other embodimentsof this aspect include corresponding computer systems, methods, andcomputer programs recorded on one or more computer storage devices, eachconfigured to perform the actions of the operations. The computer systemmay include one or more computers and can be configured to performparticular operations or actions by virtue of having software, firmware,hardware, or a combination of them installed on the system that inoperation causes or cause the system to perform the actions. One or morecomputer programs can be configured to perform particular operations oractions by virtue of including instructions that, when executed by dataprocessing apparatus, cause the apparatus to perform the actions.

The foregoing and other embodiments can each optionally include one ormore of the following features, alone or in combination. The frequencyselection module may select an amount of current as the signal toprovide to the support element. The frequency selection module maydetermine an output mode for the distributed mode loudspeaker; and mayselect the signal to provide to the support element using the determinedoutput mode. The output mode may be one of a receiver mode or ahands-free mode. The frequency selection module may select the signalthat will cause an increase in the length and the second fundamentalfrequency to be lower than the first fundamental frequency based on thefrequency selection module determining that the output mode is thereceiver mode. The frequency selection module may select the signal thatwill cause a decrease in the length and the second fundamental frequencyto be higher than the first fundamental frequency based on the frequencyselection module determining that the output mode is the hands-freemode.

In some implementations, the frequency selection module may determine atype of audio content to generate; and may select the signal to provideto the support element using the type of content to generate. The typeof audio content to generate may be one of music, a telephoneconversation, video playback, audio for a game, or a device feedbacksound. The frequency selection module may determine whether an outputvolume for a sound the load will generate satisfies a threshold volume;and may select the signal to provide to the support element based on thedetermination whether the output volume for the sound the load willgenerate satisfies the threshold volume. The frequency selection modulemay select the signal that will cause an increase in the length and thesecond fundamental frequency to be lower than the first fundamentalfrequency based on the output volume does not satisfy the thresholdvolume. The frequency selection module may select the signal that willcause a decrease in the length, and the second fundamental frequency tobe higher than the first fundamental frequency based on the outputvolume satisfying a threshold volume.

In some implementations, the distributed mode loudspeaker may include abase adjacent to a first surface of the support element opposite asecond surface of the support element that is adjacent to the supportedportion of the actuator. The support element may include anelectroactive element that includes the first surface and an adjustmentsupport that includes the second surface, a third surface of theelectroactive element that is opposite the first surface connecting to afourth surface of the adjustment support that opposite that the secondsurface. The frequency selection module may provide the signal to theelectroactive element to cause the electroactive element to apply aforce onto the adjustment support, changing the shape of the adjustmentsupport, adjusting the size of the length and changing the firstfundamental frequency to the second fundamental frequency with which theload will generate sound waves. The electroactive element may be apiezoelectric material. The electroactive element may be a material witha low latency reaction. The adjustment support may be an elastomer. Theelastomer may be one of neoprene or a silicon compound. The actuator maybe piezoelectric material. The length of the cantilevered portion and asecond length of the supported portion may be along the same axis of thedistributed mode loudspeaker. A total length of the actuator may besubstantially fixed. The total length may be a sum of the first lengthand the second length. The frequency selection module may be a digitalsignal processor. The display may be the load.

Among other advantages, the systems and methods described below mayallow a distributed mode loudspeaker to generate sounds in a wider rangeof frequencies, with a higher volume, or both, compared to othersystems. For instance, a distributed mode loudspeaker may dynamicallyselect a fundamental frequency to use when generating a sound based onan output mode, content included in the sound, a volume of the sound, ora combination of two or more of these. Generation of sounds in a widerrange of frequencies, dynamic selection of an actuator fundamentalfrequency, or both, may allow a distributed mode loudspeaker to moreaccurately reproduce sounds, e.g., closer to an original presentation ofthe sound, generate higher volume sounds, or both.

The details of one or more implementations of the subject matterdescribed in this specification are set forth in the accompanyingdrawings and the description below. Other features, aspects, andadvantages of the subject matter will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-C show an example of a device that includes a distributed modeloudspeaker.

FIG. 2 depicts a graph of frequency versus sound pressure level for twodifferent fundamental frequencies.

FIGS. 3A-B show an example of a distributed mode loudspeaker with asupport element that, upon changing shape, changes a length of acantilevered portion of an actuator.

FIG. 4 is a flow diagram of a process for changing a fundamentalfrequency of an actuator.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIGS. 1A-C show an example of a device 100 that includes a distributedmode loudspeaker 102. The device 100, such as a smartphone or anothertype of computer, uses the distributed mode loudspeaker 102, shown inFIG. 1C, to generate sound. The sound may be any type of sound, such asa phone conversation, music, an audio stream, sound for a video, orsound for a game. The device 100 may be any appropriate type of devicethat includes a distributed mode loudspeaker 102.

The distributed mode loudspeaker 102 includes a panel 104 that vibratesand generates sound waves. The panel 104 may be any appropriate panelincluded in the device 100 that can generate sound waves. For instance,the panel 104 may be a display panel included in the device 100. Thedisplay panel may include a touch screen or any other appropriate typeof display.

The distributed mode loudspeaker 102 includes a support molding 106 thatconnects the panel 104 to an actuator 110, e.g., a distributed modeactuator. For instance, the support molding 106 is rigidly connected tothe panel 104, the actuator 110, or both, to enable the support molding106 to transfer a force, generated by the actuator 110, to the panel 104and to cause the panel to generate sound. For the avoidance of doubt,the term “support molding” should not be taken to mean that the supportmolding must be manufactured, in whole or in part, by a molding process.

In some implementations, one or more other components may be part of theconnection between the panel 104 and the support molding 106. Forexample, the support molding 106 may rigidly connect to a chassis 112that rigidly connects to the panel 104. In some examples, the chassis112 is not part of the distributed mode loudspeaker 102. In someexamples, the chassis 112 is part of the distributed mode loudspeaker.

The distributed mode loudspeaker 102 can adjust a resonance mode of theactuator 110 using a support element 108. The support element 108 mayinclude one or more layers, as described in more detail with referenceto FIGS. 3A-B, that are each parallel to the panel 104. One or more ofthe layers may have consistent properties, constant properties, or both,throughout the layer. For instance, upon receiving an input signal, aspatial volume of the support element 108, or a layer included in thesupport element 108, may uniformly change throughout the support element108. The spatial volume may uniformly increase in response to receipt ofthe input signal. The spatial volume may uniformly decrease in responseto receipt of the input signal.

The distributed mode loudspeaker 102 may adjust the resonance mode ofthe actuator 110 by changing a length of the support element 108, e.g.,by increasing a spatial volume of the support element, which in turnchanges a first length L₀ of a supported portion of the actuator 110 anda length L₁ of a cantilevered portion of the actuator 110. Theadjustment of the resonance mode of the actuator 110 may optimizeperformance of the actuator 110 for generating sounds in variousfrequency ranges, e.g., may enable the actuator 110 to generate soundswith a greater decibel level for a particular output frequency.

For example, when the distributed mode loudspeaker 102 decreases thelength of the support element 108 and the length L₀ of the supportedportion of the actuator 110, the distributed mode loudspeaker 102reduces the fundamental frequency F₀ of the actuator 110 by increasingthe length L₁ of the cantilevered portion of the actuator 110. Thisreduction in the fundamental frequency F₀ may increase the low bandwidthextension of the distributed mode loudspeaker 102, e.g., enable thedistributed mode loudspeaker 102 to generate higher volume, lowerfrequency sound. An example of the increase in low bandwidth extensionis shown by a first line 202 in a graph 200 shown in FIG. 2, compared tothe second line 204 with a decreased low bandwidth extension. Thedistributed mode loudspeaker 102 may use a longer length L₁ cantileveredportion of the actuator 110 in a receiver mode, e.g., when generatingsounds around 300 Hz, when the panel 104 is near a user's ear (e.g. incontact with the user's ear), or both. In some examples, the distributedmode loudspeaker 102 may use the longer length L₁ cantilevered portionwhen generating sounds between 200 and 300 Hz.

FIG. 2 depicts a graph 200 of frequency versus sound pressure level fortwo different fundamental frequencies. For example, an actuator with alower fundamental frequency F₀ and a longer length L₁ cantileveredportion may have frequency represented by the first line 202. Anactuator with a higher fundamental frequency F₀ and a shorter length L₃cantilevered portion may have frequency represented by the second line204.

Returning to FIGS. 1A-C, when the distributed mode loudspeaker 102increases the length of the support element 108, as shown in the changefrom time T₀ in FIG. 1B to the time T₁ FIG. 1C, the length L₀ of thesupported portion of the actuator 110 increases to L₂ and the length L₁of the cantilevered portion of the actuator 110 decreases to L₃. Thisdecrease in the length of the cantilevered portion of the actuator to L₃increases the fundamental frequency F₀ of the actuator 110 which mayincrease the high bandwidth extension of the distributed modeloudspeaker 102, e.g., enable the distributed mode loudspeaker 102 togenerate higher volume, higher frequency sound. An example of theincrease in high bandwidth extension is shown by the second line 204 inthe graph 200 shown in FIG. 2, compared to the first line 202 with adecreased high bandwidth extension. The distributed mode loudspeaker 102may use a shorter length L₃ cantilevered portion of the actuator in ahands free mode, e.g., when generating sounds around 450 Hz, when thedevice is in a “speakerphone” mode, or both. In some examples, thedistributed mode loudspeaker 102 may use the shorter length L₃cantilevered portion when generating sounds between 350 and 20 kHz.

The distributed mode loudspeaker 102 includes a frequency selectionmodule that determines a desired fundamental frequency F₀ for theactuator 110 when the distributed mode loudspeaker 102 generates asound. The frequency selection module uses the desired fundamentalfrequency F₀ to determine a length for the cantilevered portion of theactuator 110. The frequency selection module may allow the distributedmode loudspeaker 102 to automatically adjust the length of thecantilevered portion of the actuator 110 depending on the output mode ofthe distributed mode loudspeaker 102 and a corresponding optimal outputfrequency range for that output mode.

When the desired length for the cantilevered portion of the actuator 110is the same as the current length of the cantilevered portion, thefrequency selection module may determine not to change the length of thecantilevered portion. For instance, during time period T₀ when thecantilevered portion has length L₁, the frequency selection module mayreceive an input signal for the distributed mode loudspeaker 102. Thefrequency selection module uses the input signal to determine a desiredfundamental frequency F₀ for the actuator 110 and a length for thecantilevered portion that will cause the actuator 110 to have thedesired fundamental frequency F₀. When the determined length is the sameas the current length L₁ of the cantilevered portion of the actuator110, the frequency selection module determines not to change the lengthof the cantilevered portion of the actuator 110.

When the determined length of the cantilevered portion of the actuator110 is different than the current length, the frequency selection modulesends a signal to the support element 108 to cause a change in size ofthe support element to change the length of the cantilevered portion ofthe actuator 110. For example, the frequency selection module mayreceive an input signal for the distributed mode loudspeaker 102 duringtime period T₀ when the cantilevered portion has length L₁. Thefrequency selection module uses the input signal to determine that thecantilevered portion should have length L₃ for the distributed modeloudspeaker 102 to generate sound based on the input signal. Since thecurrent length L₁ is different than the needed length L₃, the frequencyselection module sends a signal to the support element 108 to cause thesupport element 108 to change shape and to change the length of thecantilevered portion of the actuator 110 from L₁ to L₃. When the supportelement 108 receives the signal during time period T₁, the supportelement 108 changes shape, e.g., becomes longer, which causes the lengthof the cantilevered portion of the actuator 110 to change. For instance,the length of the cantilevered portion of the actuator 110 may decreasefrom L₁ to L₃ as shown in FIGS. 1B-C.

FIGS. 3A-B show an example of a distributed mode loudspeaker 300 with asupport element 306 that, upon changing shape, changes a length of acantilevered portion 308 b of an actuator 308. The distributed modeloudspeaker 300 may be used in the device 100, e.g., as the distributedmode loudspeaker 102. The distributed mode loudspeaker 300 includes apanel 302, e.g., such as the panel 104.

A base bracket 304, included in the distributed mode loudspeaker 300,connects a support molding 310 and the actuator 308 to the panel 302.For instance, the base bracket 304 may be rigidly connected to thesupport molding 310 during manufacturing of the distributed modeloudspeaker 300. The base bracket 304 may be rigidly connected to thepanel 302 during manufacturing of the distributed mode loudspeaker 300.The connections between the base bracket 304 and both the panel 302 andthe support molding 310 are sufficient to allow the base bracket 304 totransfer a force, generated by the actuator 308, from the supportmolding 310 to the panel 302 to cause the panel 302 to generate sound.

As shown in FIGS. 3A-B, the support molding 310 may surround theactuator 308 to hold the actuator 308 in place. The support molding 310may be rigidly connected to the actuator 308 to transfer the force,generated by the actuator 308, from the actuator 308 to the base bracket304 and the panel 302.

In some implementations, the distributed mode loudspeaker 300 includesone or more other components between the base bracket 304 and the panel302. For instance, the distributed mode loudspeaker 300 may include achassis that rigidly connects the base bracket 304 and the panel 302.

In some implementations, a system that includes the distributed modeloudspeaker 300 includes one or more other components between the basebracket 304 and the panel 302. For example, the system may include achassis that rigidly connects the base bracket 304 and the panel 302,the latter two of which are included in the distributed mode loudspeaker300.

The distributed mode loudspeaker 300 includes a support element 306. Thesupport element 306 may include one or more layers that enable thesupport element 306 to change shape, e.g., spatial volume, in responseto receipt of a signal. For instance, the support element 306 mayinclude an electroactive element 306 a and an adjustment support 306 b,e.g., as one or more layers included in the support element 306.

The combination of the electroactive element 306 a and the adjustmentsupport 306 b may cause the support element 306 to be a variablecompliance support assembly. For example, when a frequency selectionmodule included in the distributed mode loudspeaker 300 applies acontrol voltage to the electroactive element 306 a, the electroactiveelement 306 a may have a z-dimension displacement that compresses theadjustment support 306 b, e.g., commensurately with the applied voltage.Compression of the adjustment support 306 b causes the adjustmentsupport 306 b to change shape, e.g., causes a width, a length, or both,of the adjustment support 306 b to increase. The change in shape of theadjustment support 306 b increases a first length of a supported portion308 a of the actuator 308 and decrease a second length of thecantilevered portion 308 b of the actuator 308. The change in the secondlength of the cantilevered portion 308 b of the actuator 308 causes achange in the fundamental frequency F₀ of the actuator 308. For example,a change in compliance, e.g., a property such as spatial volume or shapeor both, of the support element 306 may change the effective length ofthe adjustment support 306 b and allow the fundamental frequency F₀ ofthe actuator 308 to be adjusted within the operating limits of thedistributed mode loudspeaker 300.

Use of the support element 306, with the electroactive element 306 a andthe adjustment support 306 b, by the distributed mode loudspeaker 300may allow the distributed mode loudspeaker to automatically adjust itsfundamental frequency F₀ based on the output mode of the distributedmode loudspeaker 300, e.g., an optimal output frequency range. Becausedifferent output modes may have different output frequency ranges, thedistributed mode loudspeaker 300 may use the optimal frequency range fora particular output mode to adjust the fundamental frequency F₀ of theactuator 308 for that optimal frequency range. For instance, ahands-free output mode may have a lower optimal frequency range than areceiver output mode. The distributed mode loudspeaker 300 may select alower fundamental frequency F₀ for a hands-free output mode compared toa higher fundamental frequency F₀ for a receiver output mode.

A device, e.g., the distributed mode loudspeaker 300 or a device thatincludes the distributed mode loudspeaker 300, can monitor the frequencyresponse of a sound generated by the distributed mode loudspeaker 300 inthe near-field to determine a mechanical coupling of the device, e.g.,if the device is being used as in receiver mode or in hands-free mode.The distributed mode loudspeaker 300 can use the frequency response toadjust the fundamental frequency F₀ to optimize performance of thedistributed mode loudspeaker 300 depending upon the mechanical couplingof the device. For instance, the device may determine if the device islikely handheld and in receiver mode or the device is likely contactinga surface and in hands-free mode. The device may use a result of thisdetermination to determine whether to change a fundamental frequency F₀of the actuator 308.

In some implementations, the device or the distributed mode loudspeaker300 can determine the current output mode of the device by monitoringone or more applications running on the device, e.g., a phoneapplication, a music application, a video application, etc. Theapplications running on the device may indicate the content included inan output sound for the distributed mode loudspeaker 300 to generate.The device, e.g., the distributed mode loudspeaker 300, may use data forthe one or more applications to determine the current output mode, afundamental frequency F₀ for the actuator 308, or both. The data for theone or more applications may indicate which applications are executingon the device, which applications are generating sound, whichapplications recently received user input, or a combination of two ormore of these. For instance, the distributed mode loudspeaker 300 mayincrease the length of the cantilevered portion 308 b when generatingsound for a music application or a video application that should bepresented in hands-free mode. The distributed mode loudspeaker 300 maydecrease the length of the cantilevered portion 308 b when generatingsound for a phone application that should be presented in receiver mode.

In some examples, the distributed mode loudspeaker 300 may determine anoutput fundamental frequency F₀ for the actuator 308 using one or moreproperties for a user of a device that includes the distributed modeloudspeaker 300, e.g., in addition to or instead of using data for oneor more applications executing on the device. For example, when a deviceis typically in a receiver mode for a phone conversation, thedistributed mode loudspeaker 300 may use a longer length cantileveredportion 308 b of the actuator 308 compared to a length that would beused for a hands-free mode. When a device is typically in a hands-freemode for a phone conversation, the distributed mode loudspeaker 300 mayuse a shorter length cantilevered portion 308 b of the actuator 308compared to a length that would be used for a receiver mode. The one ormore properties for the user may be determined based on user input,analysis of user interaction with the device, e.g., historical data, orboth.

In some implementations, the distributed mode loudspeaker 300 may adjustthe fundamental frequency F₀ of the actuator 308 based on a volume ofsound for the distributed mode loudspeaker 300 to generate. Forinstance, the distributed mode loudspeaker 300 may select a higherfundamental frequency F₀ for generation of higher volume sounds. Thedistributed mode loudspeaker may select a lower fundamental frequency F₀for generation of lower volume sounds.

In some implementations, the distributed mode loudspeaker 300 maydetermine whether, with a current fundamental frequency F₀ of theactuator, a sound generated by the distributed mode loudspeaker 300 willsatisfy a threshold volume. When the sound generated by the distributedmode loudspeaker 300 will satisfy a threshold volume, e.g., is greaterthan or equal to the threshold volume, based on the current fundamentalfrequency F₀, the distributed mode loudspeaker 300 may determine not tochange the length of the cantilevered portion 308 b or determine todecrease the length of the cantilevered portion 308 b and increase thefundamental frequency F₀ of the actuator 308. When the sound generatedby the distributed mode loudspeaker will not satisfy the thresholdvolume, e.g., is less than or equal to the threshold volume, based onthe current fundamental frequency F₀, the distributed mode loudspeaker300 may determine to increase the length of the cantilevered portion 308b and decrease the fundamental frequency F₀ of the actuator 308.

The electroactive element 306 a is made from an element that physicallyreacts based on an input signal. The input signal may be heat, charge,or both. The electroactive element 306 a may have a low latency reactiontime. The electroactive element 306 a may be a polymer. In someexamples, the electroactive element 306 a may be a piezoelectricmaterial. For instance, the electroactive element 306 a may be a ceramicor crystalline piezoelectric material. Examples of ceramic piezoelectricmaterials include barium titanate, lead zirconium titanate, bismuthferrite, and sodium niobate, for example. Examples of crystallinepiezoelectric materials include topaz, lead titanate, lithium niobate,and lithium tantalite.

The adjustment support 306 b may be made from an element that changesspatial volume shape in response to pressure. For instance, theadjustment support 306 b may be made from a material with consistent,constant, or both, properties throughout the adjustment support 306 b toallow the adjustment support 306 b to change shape consistently uponreceipt of pressure by the electroactive element 306 a. The adjustmentsupport 306 b may be an elastomer, e.g., neoprene or a silicon compound.

FIG. 4 is a flow diagram of a process 400 for changing a fundamentalfrequency of an actuator. For example, the process 400 can be used bythe distributed mode loudspeaker 102 or the distributed mode loudspeaker300.

A distributed mode loudspeaker receives a signal representing a sound togenerate (402). For example, a frequency selection module, included inthe distributed mode loudspeaker, may receive a signal that identifiesthe sound to generate. The signal may be any appropriate type of signalfor a speaker, a distributed mode loudspeaker, or both. The frequencyselection module may receive the input from an application executing ona device, e.g., a phone or music application on a smartphone. The devicemay include the distributed mode loudspeaker, e.g., a smartphone thatincludes the distributed mode loudspeaker. The distributed modeloudspeaker may be separate from and connected to the device, e.g., by acable or wirelessly.

The distributed mode loudspeaker determines an output mode, a volume forthe sound, content included in the sound, or a combination of two ormore of these (404). For instance, the frequency selection module maydetermine one or more of the output mode, the volume for the sound, orthe content included in the sound. In some examples, the frequencyselection module may determine one or more of the output mode, thevolume for the sound, or the content included in the sound by analyzingthe received signal. The frequency selection module may receive datathat identifies one or more of the output mode, the volume for thesound, or the content included in the sound. For instance, the frequencyselection module may receive the data from the device. The data may beincluded in the received signal or received separately from the signal.

The distributed mode loudspeaker determines whether to change a currentfundamental frequency of an actuator based on an output mode, a volumefor the sound, content included in the sound, or a combination of two ormore of these (406). For example, the frequency selection moduledetermines whether the current fundamental frequency of the actuatorincluded in the distributed mode loudspeaker is an optimal fundamentalfrequency to use when generating the sound. The distributed modeloudspeaker, e.g., the frequency selection module, may use one or moreof the output mode, the volume for the sound, or the content included inthe sound when determining whether the current fundamental frequency ofthe actuator is an optimal fundamental frequency to use when generatingthe sound.

In response to determining to change the current fundamental frequencyof the actuator, the distributed mode loudspeaker determines an updatedfundamental frequency for the actuator (408). The distributed modeloudspeaker, e.g., the frequency selection module, may determine theupdated fundamental frequency using one or more of the output mode, thevolume for the sound, or the content included in the sound. In someexamples, the distributed mode loudspeaker may use a frequency orfrequency range to determine the updated fundamental frequency.

The updated fundamental frequency may be an optimal fundamentalfrequency for the actuator to use when generating the sound. Forinstance, the optimal fundamental frequency may allow the distributedmode loudspeaker to generate a higher volume sound, more accuratelyreproduce the sound, or both, compared to other fundamental frequencies.

The distributed mode loudspeaker sends a signal to a support element tocause the support element to change shape and change the currentfundamental frequency of the actuator to the updated fundamentalfrequency (410). For example, the frequency selection module may sendthe signal to the support element to cause the support element to changeshape. The signal may be a particular current, heat, or both.

The distributed mode loudspeaker, e.g., the frequency selection module,may determine an amount of current, an amount of heat, or both, toprovide to the support element based on the updated fundamentalfrequency. For instance, the amount of current may indicate the degreeto which the current fundamental frequency must change so that theactuator has the updated fundamental frequency.

In some implementations, the distributed mode loudspeaker, e.g., thefrequency selection module, may determine a change in current, a changein heat, or both, to provide to the support element based on the updatedfundamental frequency. When the distributed mode loudspeaker is alreadyproviding a current, heat, or both, to the support element to maintain ashape, a spatial volume, or both, of the support element, and acorresponding fundamental frequency of the actuator, the distributedmode loudspeaker may determine an increase or a decrease in the current,heat, or both, provided to the support element so that the actuator willhave the updated fundamental frequency.

The distributed mode loudspeaker provides an activation signal to theactuator (412). For example, the distributed mode loudspeaker mayprovide an activation signal to one or more electrodes included in theactuator that cause the actuator to actuate and generate a force. Thesignal may be a current. When the distributed mode loudspeaker sends asignal to the support element, the distributed mode loudspeaker mayprovide the activation signal to the actuator after changing the currentfundamental frequency of the actuator to the updated fundamentalfrequency.

When the distributed mode loudspeaker determines not to change thecurrent fundamental frequency of the actuator, the distributed modeloudspeaker provides the activation signal to the actuator withoutchanging the fundamental frequency of the actuator. For instance, thedistributed mode loudspeaker provides current to the actuator afterreceiving the signal representing the sound to generate and withoutsending a signal to the support element based on the signal.

The distributed mode loudspeaker may include a drive module thatprovides the current to the one or more electrodes included in theactuator. The drive module may be the same component as the frequencyselection module. The drive module may be a different component,included in the distributed mode loudspeaker, from the frequencyselection module.

The distributed mode loudspeaker generates a force with the actuator(414). For example, the actuator receives the activation signal andactuates, which causes the actuator to generate a force. Receipt of acurrent by electrodes included in the actuator may cause the actuator toactuate and generate the force.

The distributed mode loudspeaker provides the force to a load togenerate the sound (416). For instance, a rigid connection between theactuator and a support molding may cause the actuator to provide atleast some of the generated force to the support molding. A rigidconnection between the support molding and a panel may cause the supportmolding to provide at least some of the generated force to the panel.The rigid connection between the support molding and the panel mayinclude a base bracket that transfers at least some of the force fromthe support molding to the panel.

In some implementations, the process 400 can include additional steps,fewer steps, or some of the steps can be divided into multiple steps.For example, the distributed mode loudspeaker may determine whether tochange a current fundamental frequency of an actuator, determine theupdated fundamental frequency, and send the signal to the supportelement to cause the support element to change the current fundamentalfrequency to the updated fundamental frequency without performing theother steps of the process 400.

In some implementations, one or more of the components described in thisdocument can be included in devices other than a distributed modeloudspeaker. For example, a haptic feedback system may use the actuator,e.g., the distributed mode actuator, the support element, the frequencyselection module, or a combination of two or more of these, to generatehaptic feedback. The haptic feedback system may use the actuator togenerate energy in a frequency range between 250 Hz and 300 Hz. Thehaptic feedback system may be included in a device, e.g., thedistributed mode loudspeaker described above. The haptic feedback systemmay use an actuator that also generates energy for use creating sound,e.g., when the haptic feedback system and a distributed mode loudspeakeruse the same actuator for different types of output.

In some implementations, when the distributed mode loudspeaker isincluded in a smartphone, the smartphone may include a display, e.g., adisplay panel, one or more processors, and one or more memories. Thedisplay may be a load used by the distributed mode loudspeaker togenerate sound. In some examples, the smartphone may include a loaddifferent from the display for the distributed mode loudspeaker to usewhen generating a sound.

The memories may store instructions for an application, e.g., from whichthe distributed mode loudspeaker can receive the input identifying thesound to output. The one or more processors, e.g., one or moreapplication processors, may use the instructions stored on the one ormore memories to execute the application. During execution of theapplication, e.g., a phone application or a music application or a game,the application may determine a sound to output to a user. Theapplication provides, to the distributed mode loudspeaker, data for thesound.

The frequency selection module or the drive module or both, included inthe distributed mode loudspeaker, receive the data for the sound asinput. The frequency selection module may be the same component in thesmartphone as the drive module. In some examples, the frequencyselection module is a different component in the smartphone from thedrive module. The frequency selection module uses the data for the soundto determine whether to change a current fundamental frequency of anactuator included in the distributed mode loudspeaker and, if necessary,provides a signal to a support element included in the distributed modeloudspeaker. The drive module provides current to one or more electrodepairs included in the distributed mode loudspeaker after any change tothe current fundamental frequency for generation of the sound.

In some examples, the one or more processors, the one or more memories,or both, are separate from the drive module, the frequency selectionmodule, or both. For example, the frequency selection module, the drivemodule, or both, may include at least one processor, at least onememory, or both. The at least one processor may be a different set ofprocessors from the one or more processors. The at least one memory maybe a different memory from the one or more memories.

Embodiments of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, in tangibly-embodied computer software or firmware, incomputer hardware, including the structures disclosed in thisspecification and their structural equivalents, or in combinations ofone or more of them. Embodiments of the subject matter described in thisspecification can be implemented as one or more computer programs, i.e.,one or more modules of computer program instructions encoded on atangible non-transitory program carrier for execution by, or to controlthe operation of, data processing apparatus. Alternatively or inaddition, the program instructions can be encoded on anartificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. The computer storage mediumcan be a machine-readable storage device, a machine-readable storagesubstrate, a random or serial access memory device, or a combination ofone or more of them.

The term “data processing apparatus” refers to data processing hardwareand encompasses all kinds of apparatus, devices, and machines forprocessing data, including by way of example a programmable processor,or multiple processors. The apparatus can also be or further includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application-specific integrated circuit). Theapparatus can optionally include, in addition to hardware, code thatcreates an execution environment for computer programs, e.g., code thatconstitutes processor firmware, a protocol stack, an operating system,or a combination of one or more of them.

For example, a distributed mode loudspeaker, e.g., a frequency selectionmodule or a drive module or both, may include a data processingapparatus. The distributed mode loudspeaker may use the data processingapparatus, in conjunction with at least one memory, to perform one ormore of the operations described in this document.

A computer program, which may also be referred to or described as aprogram, software, a software application, a module, a software module,a script, or code, can be written in any form of programming language,including compiled or interpreted languages, or declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment. A computer program may, butneed not, correspond to a file in a file system. A program can be storedin a portion of a file that holds other programs or data, e.g., one ormore scripts stored in a markup language document, in a single filededicated to the program in question, or in multiple coordinated files,e.g., files that store one or more modules, sub-programs, or portions ofcode. A computer program can be deployed to be executed on one computeror on multiple computers that are located at one site or distributedacross multiple sites and interconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable computers executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Computers suitable for the execution of a computer program include, byway of example, general or special purpose microprocessors or both, orany other kind of central processing unit. Generally, a centralprocessing unit will receive instructions and data from a read-onlymemory or a random access memory or both. The essential elements of acomputer are a central processing unit for performing or executinginstructions and one or more memory devices for storing instructions anddata. Generally, a computer will also include, or be operatively coupledto receive data from or transfer data to, or both, one or more massstorage devices for storing data, e.g., magnetic, magneto-optical disks,or optical disks. However, a computer need not have such devices.Moreover, a computer can be embedded in another device, e.g., a mobiletelephone, a personal digital assistant (PDA), a mobile audio or videoplayer, a game console, a Global Positioning System (GPS) receiver, or aportable storage device, e.g., a universal serial bus (USB) flash drive,to name just a few.

Computer-readable media suitable for storing computer programinstructions and data include all forms of non-volatile memory, mediaand memory devices, including by way of example semiconductor memorydevices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks,e.g., internal hard disks or removable disks; magneto-optical disks; andCD-ROM and DVD-ROM disks. The processor and the memory can besupplemented by, or incorporated in, special purpose logic circuitry.

A distributed mode loudspeaker may include one or more memories thatstore instructions which, when executed by the distributed modeloudspeaker, cause the distributed mode loudspeaker to perform one ormore operations described in this document. For instance, theinstructions may cause the distributed mode loudspeaker, e.g., afrequency selection module, to determine an output frequency subset,energize one or more electrodes, or both. In some examples, thefrequency selection module or a drive module or both may include the oneor more memories or some of the one or more memories.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., an LCD (liquid crystal display) monitor,for displaying information to the user and a keyboard and a pointingdevice, e.g., a mouse or a trackball, by which the user can provideinput to the computer. Other kinds of devices can be used to provide forinteraction with a user as well; for example, feedback provided to theuser can be any form of sensory feedback, e.g., visual feedback,auditory feedback, or tactile feedback; and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of what may beclaimed, but rather as descriptions of features that may be specific toparticular embodiments. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various system modulesand components in the embodiments described above should not beunderstood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Particular embodiments of the subject matter have been described. Otherembodiments are within the scope of the following claims. For example,the actions recited in the claims can be performed in a different orderand still achieve desirable results. As one example, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In some cases, multitasking and parallel processing may beadvantageous.

What is claimed is:
 1. A system comprising: an actuator for aloudspeaker that has a total length and includes: a first portion having(i) a first end adapted to contact, across an area, an adjustable-shapesupport element, and (ii) a first length that, during operation of theactuator, changes in dimension to cause a change in size of the areaacross which the first end contacts the adjustable-shape support elementin response to a change in the shape of the adjustable-shape supportelement, and a second portion (a) adapted to create, during operation ofthe actuator, a force to cause vibration of a load to generate soundwaves using a fundamental frequency and (b) having a second length that,based on a change to the dimension of the first length and the size ofthe area during operation of the actuator, changes in dimension andchanges a fundamental frequency at which the load will generate soundwaves.
 2. The system of claim 1, wherein the total length of theactuator is substantially fixed and the total length comprises a sum ofthe first length and the second length.
 3. The system of claim 1,comprising: the adjustable-shape support element that changes shape uponreceipt of a control signal; and a base adjacent to a first surface ofthe adjustable-shape support element opposite a second surface of theadjustable-shape support element that contacts the first portion of theactuator.
 4. The system of claim 3, wherein the adjustable-shape supportelement changes shape upon receipt of current.
 5. The system of claim 3,wherein the adjustable-shape support element comprises: an electroactiveelement that includes the first surface; and an adjustment support thatincludes the second surface, a third surface of the electroactiveelement that is opposite the first surface connecting to a fourthsurface of the adjustment support that opposite that the second surface.6. The system of claim 5, wherein the electroactive element comprises amaterial with a low latency reaction.
 7. The system of claim 5, whereinthe adjustment support comprises an elastomer.
 8. The system of claim 3,comprising: a data processing apparatus to provide the control signal tothe adjustable-shape support element to cause the adjustable-shapesupport element to change shape.
 9. The system of claim 8, wherein thedata processing apparatus is adapted to select an amount of current asthe control signal to provide to the adjustable-shape support element.10. The system of claim 9, wherein the data processing apparatus isadapted to: determine an output mode for the loudspeaker; and select thecontrol signal to provide to the adjustable-shape support element usingthe determined output mode.
 11. The system of claim 10, wherein theoutput mode comprises one of a receiver mode or a hands-free mode. 12.The system of claim 8, wherein the data processing apparatus is adaptedto: determine whether an output volume for a sound the load willgenerate satisfies a threshold volume; and select the control signal toprovide to the adjustable-shape support element based on thedetermination whether the output volume for the sound the load willgenerate satisfies the threshold volume.
 13. The system of claim 12,wherein the data processing apparatus is adapted to select the controlsignal that will cause a) an increase in the dimension of the secondlength and b) the fundamental frequency to be lower than an initialfundamental frequency when the output volume does not satisfy thethreshold volume.
 14. The system of claim 12, wherein the dataprocessing apparatus is adapted to select the control signal that willcause a) a decrease in the dimension of the second length and b) thefundamental frequency to be higher than an initial fundamental frequencywhen the output volume satisfies a threshold volume.
 15. The system ofclaim 1, wherein the actuator comprises piezoelectric material.
 16. Thesystem of claim 1, wherein the first length of the first portion and thesecond length of the second portion are along the same axis of theloudspeaker.
 17. A method comprising: in response to a change in a shapeof an adjustable-shape support element that contacts a first portion ofan actuator across an area and during operation of the actuator for aloudspeaker, adjusting a first length of the first portion of theactuator to change a size of the area; based on adjusting the firstlength of the first portion of the actuator to change the size of thearea and during operation of the actuator for the loudspeaker, adjustinga second length of a second portion of the actuator that is adapted tocreate, during operation of the actuator, a force to cause vibration ofa load to generate sound waves using a fundamental frequency (a) atwhich the load will generate sound waves (b) that changes based on thesecond length of the second portion; receiving, by the actuator, anactivation signal; and in response to receipt of the activation signal,generating, by the actuator and using the fundamental frequencydetermined by the second length of the second portion, a force thatvibrates a load which generates the sound waves.